David Cameron will attempt to appease Conservative Eurosceptics tomorrowwhen he outlines plans to repatriate some powers from Brussels as part of a toughening of Britain's relations with the EU.

Amid anger on the right of his party at his decision to abandon a "cast-iron guarantee" to hold a referendum on the Lisbon treaty hours after the Czech Republic ratified it, Cameron will say he is prepared for a battle with the EU.

Conservative MPs have been called to a meeting with Cameron at 2.45pm tomorrow where the Tory leader will pledge to repatriate social and employment powers to Britain, effectively restoring the British opt out from the social chapter. This would need the agreement of all 27 EU members because the provisions in the social chapter have been sprinkled through EU treaties which can only be amended unanimously.

Cameron, who may indicate that he would be prepared to veto negotiations next year on the EU budget and reform of the Common Agricultural Policy if his demands are rejected, may also keep open the option of holding a referendum on Britain's future relations with the EU.

The Tory leader, who will deliver a speech in Westminster after his meeting with his MPs, has prepared carefully for tomorrow'safter he was accused by the Tory right of breaking his pledge to hold a referendum on the Lisbon treaty. In an article for the Sun on 26 September 2007, Cameron wrote: "Today, I will give this cast-iron guarantee: If I become PM a Conservative government will hold a referendum on any EU treaty that emerges from these negotiations. No treaty should be ratified without consulting the British people in a referendum."

William Hague, the shadow foreign secretary, abandoned this position today hours after Václav Klaus, the Czech president, signed the treaty. Hague said: "What has happened means it is no longer possible to have a referendum on the Lisbon treaty."

Barry Legg, co-chair of the Eurosceptic Bruges Group, said: "David Cameron needs to come clean with the British people: why is he breaking his pledge to hold a referendum on the Lisbon treaty?"Lord Mandelson, the business secretary, told Sky News: "It looks as if that cast-iron guarantee has become very rusty indeed. I don't think he's being entirely honest with the British people."